The present invention relates to the processing of copper tubing; and more particularly, the invention relates to such processing following drawing and sizing.
It is known to process copper tubing for purposes of sizing by means of press-working and rolling followed by drawing under utilization of a drawing oil. The finished tubing is then heated in order to evaporate that oil, which procedure requires, of course, the removal of the oil vapor from the interior of the tubing. The removal in question involves, in particular, also the removal of carbon-containing deposits in the tubing. Such deposits may result from annealing of a tube. German printed patent application Ser. No. 26 17 406 proposes heating of the tubing to about 500.degree. to 550.degree. centigrade and passing of a carrier gas through the tubing, capturing and removing the oil vapor. Subsequently, the tubing is heated to 650.degree. C., for an extended period of time for purposes of soft-annealing, i.e. process annealing, because it is desirable to render the tubing soft and readily bendable, a feature that is needed for installations in homes and the like. This particular method is quite suitable, especially as far as the removal of oil vapor deposits is concerned; but it cannot be carried out on a continuous basis and is, thus, not economical.